In the meantime, let's take a look at a very interesting 1958 cartoon by Władysław Nehrebecki, best known for his "Bolek and Lolek" series.
This seemingly typical cat-and-mouse cartoon is in fact a bold graphic experiment; it just wouldn't work without its modern, abstract design (which is fully animated, to boot!). The cat is literally a yarn-like drawing that manages to escape its paper (and can be seen through), and even the solidly-colored mouse is drawn flatly; there's some real innovation in the settings, especially in the chase from 5:39 to 5:58.
As a whole, the cartoon is *almost* what a Tom and Jerry cartoon by UPA would be like, down to eschewing violence; creativity is found elsewhere, like in the aforementioned chase or even in this cartoon's mouse traps, which are practically live monsters. The music is at times very reminiscent of Scott Bradley's scores for the mid-50s Tom and Jerrys, and even some of the sound effects seem to been directly ripped from Tom and Jerry cartoons! (The springing sound at 3:35, the whisker-pull at 3:48 and 6:40 (the latter use for a piano lid opening!), the pop sound at 3:52...heck, the cat's yelping at 8:09!)
Still, it's more interesting than anything the Tom and Jerry cartoons or UPA had to offer in 1958. Enjoy!