1) Decentralized apps (dapps) - Backend of websites/service that run as smart contracts on a particular blockchain instead of a centralized infrastructure. More resilient and inherently scalable.
2) Decentralized identity - Instead of creating user accounts for every site, identities are just wallet addresses. People maintain their own data and use their own keys to sign transactions.
3) Decentralized ownership (records) - NFTs are secure records of payment for ownership of a digital asset and can be traded easily.
The theme is that everything is available and keeps running without censorship, corruption, or other influence getting in the way, as long as the chain itself is still running. Whether there's serious utility in that is still unknown. I also think it's unlikely given how much we're tied to physical bodies and sovereign nations with their own laws and politics.
think of it like Shopify apps - the SaaS products that developers try to sell to merchants to make some part of the merchant's life easier. Those developers are just trying to make money.
web3 offers a similar kind of platform that isn't dependent on Shopify continuing to care. there are many things to make easier and it is incredibly lucrative to do so.
the "decentralized" part is just a distraction to derail conversations, but degrees of decentralization are optional.