Recovering non- itunes and non- Apple Music mp3s from an iPhone

I have a sizable music library on my phone that predates iTunes and Apple Music-- they were MP3s added in to iTunes from Napster and Audiogalaxy back when those were legal. My old hard drive failed and now my phone is the only place in the world with this music on it. Is there a way to get the music off my iPhone and on to my computer so that I can store it safely?