Yeah… This is why I’m becoming less and less fond with “layer” terminology. There are different definitions and things get pretty muddled. This is how I understand the layers:
Layer 0 = the community
Layer 1 = monolithic chains
Layer 2 = rollups inheriting security from layer 1s
Polkadot isn’t all that different from Ethereum- it’s a chain of chains. I don’t know as much about Cosmos but I’m fairly certain it’s just an SDK for creating monolithic chains.
Really it should just be settlement layers, execution layers, data availability layers, and the community.