Unfortunately your logs are truncated (the lines are much longer than that, you only grabbed what was visible on your screen).
Could you try again with curl -v instead? This will make the output more verbose.
It’s expected that curl http://localhost will return nothing, because by default Caddy will set up an HTTP->HTTPS redirect for localhost, but curl does not follow redirects unless you pass the -L option (short for Location, i.e. the name of the header used for redirects).
Please don’t forget to use ``` on the lines before and after your config and logs, I went ahead and updated your post to wrap your logs as such because it makes it much easier to read.