Using Characters Created in Another Program

Hello!  I am new to using Animate, and I've been watching tutorials here and on YouTube.  I'm a teacher, and I want to create short songs with animated characters.  I would like to use some clipart characters that I've already made in PowerPoint.  Is it possible to use those characters and make them animated if they were made in another program, or do I have to remake them in Animate?  If it's possible, how would I do that?  Any help would be great. 

Thanks!