Re: How to learn a tune....
Just pick one that sounds good to you, that you like. Put any + all other version out of sight and out of mind til you have the one that you like well+truly stuck into your mental "radio player."
This stuff is folk music. It evolves. There are ENDLESS variations of most of these tunes that go back even as far as 50 years, never mind a hundred or two and more! It happens with every tune that gets played a lot, passed around a lot, played by lots of different people. Folk is probably the most highly variated. But it has also happened to the most popular jazz "standards," happens to the top pop tunes, etc. It's kinda like language- it's almost living organic evolving thing.
find one you like, make it your own, have fun with it. Then once you really know it, evolve it yourself- add or change lil things, ornaments, turnarounds, harmonization, yadda yadda ... to make it "really your own." Keep working it to put the widest smile on ya when you play it.
1976 Ibanez 511
Weber Bighorn 2-pointer, and Sweet Pea traveller
1960's Kay tenor banjo restrung to Irish tenor
Trinity College octave
... and trombones, but that's different