It sounds like you're outside your comfort zone. Jesus is not other than God [the Father or God the Spirit] in orthodox [little-o] Christian belief. It's confusing for sure.
Catholicism includes the veneration of saints but they are categorically not gods, nor are relics gods, so how can the inclusion of such elements indicate polytheism.
Interesting that you mention Islam as one of the criticisms of Islam is that many supposed adherents appear to worship Mohammed as a god, certainly as much as Catholics "worship" the beatified. There is also the notion, warned against in the Quran IIRC, of worship of the djinn which could be considered analogous in some ways with veneration of the saints.