That's reasonable for a library that just supports HTTP. It's not that difficult of a protocol, even though it appears to have 3700 commits. (Do these count the ones from Mongose where it forked from?) Even CURL is mostly just one person, and it supports everything in the world: HTTPS, HTTP/2, FTP, Gopher, dozens more...
how should i interpret this information?
That this project has bus factor = 1. High risk.
The risk isn't a function of developer count alone; for example, a simple and polished feature-complete library with one developer is lower risk than a beta version of a huge complex distributed system with 100 developers.