If you like stories about reconciling with weird sci-fi evolution of non-human intelligence (spiders, in this case), check out Children of Time by Adrian Tchaikovsky.
Going to second the poor person whose note—that the Martians in “Last and First Men” were a swarm intelligence before Lem—was downvoted out of existence. That is a strange book (and repetitive and boring) but Stapledon was a pioneer of many ideas taken up by later sci-fi
I would not put him in the same league as Lem. Or Banks or Reynolds, for that matter.
I would
Tchaikovsky is uneven, as are Banks and Reynolds. Lem is just different. He’s rarely a hard sci-fi writer and some of his books are barely sci-fi. More like Voltaire (Invincible is sci-fi)
In fact quite a lot of Lem's writing is not sci-fi at all, period. Hospital of Transfiguration is an absolutely mandatory read for any fan of Lem, even though it will leave you depressed for a week afterwards. And memoirs found in a bathtub is just a masterpiece of absurdity, it has a very good English audiobook actually if anyone wants to try.
I would rate Lem higher than those, but not sure if it's a different league.
It's not even the same sport.
The Martians in "Last and First Men" are also a swarm intelligence. Was published in 1930, 30 years before "The Invincible."