taking this thread into account [Redirect loop when rewriting / to /index.html to apply basicauth to it](http://Redirect Loop when rewriting to index) it seems the problem is using index.html in the redirect.
changing the config to
rewrite / {
to {host}{uri}home.html /proxy{uri}
}
and renaming the files from index.html to home.html (for testing) results in the correct files being served.
So the filename of index.html leads to very funny redirects.