Avant: le deluge. There was a moment, about an hour into Paris 2024’s Grand Opening Spectacular, as the rain soaked through shoes, trousers, socks and eventually skin, hair and bone; as yet more boats of waving people chugged down the Seine, like watching an endless series of weirdly nationalistic office parties; as some men did some dancing in a place, for reasons that frankly seemed quite remote at that point, where a thought occurred.

Maybe this wasn’t just the worst Olympic opening ceremony ever. Maybe this wasn’t the worst outdoor event ever. Maybe this was the worst thing ever.

Fast forward to 11.25pm local time and Paris 2024 basically brought on Messi. There may have been better moments in the meandering history of opening ceremony entertainment than Céline Dion halfway up the Eiffel Tower, just below the Olympic rings, lights cascading, 56 years old but an absolute sonic force, belting out a jaw-dropping rendition of Édith Piaf’s Hymne à l’amour.

But, well, none spring to mind right now. Sport: never over ’til it’s over. Hardest game in the world, Vegas-style big ticket showmanship. But what a way to rescue the night.

And make no mistake, this needed rescuing. It needed Céline rising from the bench to overhead scissor-volley those final five minutes into the net. Because to that point, well, it certainly didn’t look like this in the catalogue.

“By starting the ceremony at 7.30pm, we are counting on the sun and its flashes of gold to illuminate the stone and make the water sparkle.” The words, there, of Thomas Jolly, artistic director of the Paris 2024 opening ceremony, as recorded in his relentlessly upbeat manifesto.

Hmm. About that. All joshing aside, you do have to admire the bravery of the French Olympic committee in spending €120m on a ceremony that wasn’t just groundbreaking, but tinged with imperial grandeur, Emmanuel Macron’s own field of the cloth of gold, to spend years fanfaring its own importance, and then to stage the whole thing in a way that’s fatally vulnerable to a spot of summer rain.

The moment you do that, only one thing is guaranteed: it’s going to rain. And so it duly came to pass as these Games were inaugurated with a ceremony that was, as they always are, fun, silly, overly long, overly sombre. But also nice, warm, necessary, and in this case thrillingly hostage to its own hubris.

So much so that, as the rain continued to fall, there was a sense of the spectacle reasserting itself, becoming oddly heroic, a defiance of nature, at the very least extremely funny. Although, given the theme of the ceremony was by this stage no longer Paris is splendid and cool, but this is an excellent cosmic joke, it needs more from the catalogue to get the real depth of it.

“The fusion of art and sport is total,” Jolly had warned us. “On this incredible stage, they will be bathed in the most beautiful light.”

So we got a dude rocking out on a guitar on a building (in the pouring rain). We got a Jeanne d’Arc figure on a flaming warship singing Bizet, which was actually really good (in the pouring rain). We got people in wet rubber heads doing a cabaret.

“It is in this unifying, eclectic, poetic and political spirit, as heir to Jean Vilar and André Malraux, great figures of decentralisation and exceptional French culture, that I have thrown my soul into this river of creation.”

Again, to be fair to Damian Gabriac, co-author of the ceremony, he probably wasn’t thinking here about men on BMXs doing awkward tricks on a horribly slippery deck, or one of the big screens winking out as rain trickled in, bringing with it the realisation that a thing that had been basically sitting watching boats on a screen in the rain was now just sitting in the rain.

Happily there were still lovely moments. The rain had stopped half an hour before the start, the skies still bruised and grey, as Macron and Thomas Bach appeared on their plinth, Bach waving like a dentist at his own birthday party, Macron stately and cool.

There was an early plume of tricolour smoke over an illuminated bridge and you just melted a little at the beauty of Paris. The Greeks were first off leading the Dunkirk-style team flotilla, out there beaming handsomely on a barge, sprayed with fountain jets. From that point the next three hours were a kind of Glasgow Willy Wonka Experience: the French version.

Here we have Quasimodo, Les Miserables, Marie Antoinette and Mona Lisa. Here is the Folies Bergère. Here is cheese. Here is Charles Aznavour. Here are Marcel Proust, Josephine Baker and Jacques Tati.

The show was the work of 49 named creative directors, from a choreographer called Zenzel to the house of Dior. Six months of rehearsals went into this. It was complex, nuanced, fun, energetic, diffuse, diluted, and too spread out. It turns out there’s a good reason why big events are held in stadiums. How many more boats now? The best part was a wonderful interlude where Axelle Saint Cirel sang La Marseillaise on top of the Grand Palais. This was perfect and should just happen every day.

Later on the stuff that kept on happening got a bit better. Barbara Butch’s DJ set was good.

At the end the Olympic flag was brought in by a knight in shining armour and then hung, hilariously, upside down. It felt epic, as it always does. The rain added gravitas (also: water).

And yes, in the end it is just an opening ceremony. These things never have any bearing on the sport to follow. This one only came into focus because it made so much noise in advance. But what happened here was significant in its own way. By holding it in the back garden, making the city the star, Paris was trying to get maximum bang for its buck. Beyond the unintended cosmic comedy of a rain-sodden parade, beyond the gross overspend on this one element (three times what London cost), there is a sense of trying to do something different.

The next two weeks will expand on that theme. Because in almost every other front the Paris Games are a shot at something new. No carbon-heavy frippery, no risible white elephant enormo-dromes. Re-use, re-purpose, kit out the old concrete dome. Use the city, don’t fight against it.

Infrastructure costs are lower than any other Games this century. Paris still hopes to cover its outlay. The one unexpected variable is security, estimated at $300m, ramped up here by this rain-ravaged folie, and likely to at least double some experts say, given the need for military-grade equipment, drone monitoring, armoured vehicles on the street and all the rest.

This was the other unavoidable irony here. Olympics Wide Open was the motto of the night. Which is not what is happening at all behind the triple-reinforced ring of steel.

For now we’ll always have the men dancing in the rain. We’ll always have Céline. By the end, as Bach gave another generic and interminable speech, it all felt a bit like a posh country wedding; all for the best, fingers crossed, and marching on with a squelch into the next two vital weeks for these rare old summer Games.

• This article was amended on 27 July 2024. Security costs for the Paris Olympics are estimated at $300m rather than $300,000.