I ran a wild west game of 5e called Spellslinger for three years from 3rd to 15th. You can actually adapt most DnD monsters and races quite easily to a wild west them.
Dwarves - gold and mithril prospectors
Wood elves - dessert nomads
Aaracocra - native Americans although you need to be respectful obviously
Tielflings - always played piano in bars for some reason
Giants - desert giants work really naturally
It also turns out they're is an absolute ton of fantasy wild west art which serves for great inspiration.