A lot of Timon and Pumbaa’s characteristics and jokes were based on adlibs and interactions between Lane and Ernie Sabella during the recording process.
That role ultimately went to Nathan Lane, and it’s admittedly tough to picture anyone else doing the part.
While Murphy definitely had the comedic chops, the role of Timon is entirely dependent on chemistry with Pumbaa, and the same is true for the voice actors.
Entertainment Weekly had some of the cast and producers of The Lion King talk about the making of the classic animated film, and among the interesting tidbits they dropped, producer Don Hahn revealed Eddie Murphy was up for the role of Timon.