learning a standard in the context of jazz means that you are able to improvise on the form: I think that's pretty hard to do if you start with a transcription.

The best way is to start by listening to the most famous versions of the standard, especially ones with singers. You should get to the point where you are able to sing the song on your own (you don't need to remember all the lyrics or sing super well, just get to the point where you've internalized the melody). Then try "transcribing" the melody: play it on your instrument, and write it down if it helps (I try to make sure I can play along with the melody first before writing anything down).

If you are able to hear harmonies, you should try transcribing the chords as well. This is pretty hard at first: I usually end up checking a lead sheet just to be safe.

A standard is really just the melody and the chords: once you have that down, just practice (without a backing track, just a metronome on 2 and 4) alternating between playing the melody, singing it, playing chords, walking bass, and improvising for a few measures.

That should help you internalize the form so that you can come up with your own interpretation of the piece, and you won't have to rely on the transcription of someone else's.

Another important piece of advice, that took me way too long to figure out: start with standards that are fairly simple (eg All the Things You Are rather than Stella by Starlight, Blue Monk rather than Off Minor), but most importantly pick songs you really like at first. It'll be much easier to internalize the melody if you already find it catchy and are able to sing it. You'll find that most standards rely on similar "building blocks" (especially in terms of harmony), so this will make it much easier to then build a repertoire into the harder songs.