Marshall has copyright on his lyrics, you just said yourself patents and copyright are different things.
Sufficiently different rip-offs that don’t confuse consumers as being the original should be legal. They already are as far as copyright is concerned.
Many design patents should never have been registered, and should lose when defended in court. Design trademarks are a third similar issue.
Mine is in August. Figs supposedly have two harvests a year, but I must have blinked during the other one.