Floyd died for a lot of reasons his own, but he sure did get helped along by an overaggressive cop kneeling on his neck.
I don't think the cop planned on killing him, and there was no need to keep his knee on the neck like that. Floyd di himself no favors, as you suggest, and he also resisted minutes of effort by three officers trying to load him into the back of a cruiser.
Floyd was a scumbag, and the cops were scumbags to let things go the way it did. And yes, this BLM nonsense used a career criminal PoS to martyr for the ignition of their crusade, which has little to do with their true goal.. which is Marxism.