+1 on what Pat said.

Personally, I post my musical efforts here, being assured of fair and honest criticism by highly accomplished fellow musicians/songwriters, without fears of being flamed by snipers far less qualified than I.

Posting them here is like auditioning them before friends and family. I know, sans pain or tears, if a composition is worthy of more honing or amending.

I have never yet seen a posted song flamed by PGers. We have had a few trolls over the years but when they recognize the knowledge, wisdom, and talent assembled here they soon fade away.

OP, strive to be a bigger part of the PG Family and you'll worry less about plagiarism.