Did Led Zeppelin steal other musicians ideas/songs? A question only, and definitely not a statement of fact.
Haven't looked too deeply into this, but it seems there are some striking similarities between some Led Zep tracks and other tracks which predate them.
A couple of examples, Jake Holmes "Dazed and Confused" and Small Faces "You Need Loving".
Can't link to you tube because of the usual profanity problem, but I'm sure you can find them for yourselves.