Is there any other way to download the executables of core without having to build every single version separately?
I guess that I had some more patience than you
I went basically on the same path, but I've looked more carefully.
And I have something fro you:
https://bitcoin.org/bin/If you go into those subfolders, in some you'll get binaries/installers too, back to
0.10.3 0.8.6 (also see insecure folder), I hope that's old enough for your needs.