Lucy belongs on the Mount Rushmore of comedy.
Maybe, on the politically correct Mt. Rushmore of comedy.
As for Jim Carrey, off the top of my head I could probably name 10 of his peers who are arguably funnier.
I'd love to see you try.
Dude over 60 years later and she still has legions of fans and a rerun of hers beat out the finale of one of the most popular modern TV shows. She pioneered comedy and television in many ways. She belongs on that mountain.
And you really can't think of anyone funnier than Jim Carrey? Bill Murray, Robin Williams, John Goodman, Chris Rock, Chevy Chase, Adam Sandler, Chris Farley, Will Smith, Leslie Nielsen, Jerry Seinfeld. There's 10 and if I had more time I could think of plenty more.
Bill Murray - No; not close. Though, he's great at delivering under current comedy.
Robin Williams - Worthy of a mention, but no.
John Goodman -

Chris Rock - Not even close. If he were close, he wouldn't have had to have fallen back on his poor black guy schtick.
Chevy Chase - Had a great prime, but no.
Adam Sandler - This would probably be like making the case that Dominique Wilkens was better than Michael Jordan.
Chris Farley - Probably worthy of a mention, but no.
Will Smith - The only reason I don't totally dismiss this is cos of his work on 'Fresh Prince...'; but no.
Leslie Nielsen - He came on too late. Naked Guns were great, but come on now.
Jerry Seinfeld - I think his show was great, but he would tell you that he's not a great actor to begin with.