The libs team maintains very few crates as such (see the crates.io listing).
Some of the team members might maintain other crates on top of that.
Non-team members can be just as trustworthy to maintain good crates.
lib.rs is an alternative to crates.io that gives you lots more categories to find stuff in.
"Simple and common" stuff is not such a clear distinction. The use cases for Rust are far too wide spread.
You might also be interested in the recent discussion around the standard library: Rust should have a big standard library and here’s why