Do I file as a resident or non resident in Missouri, if I only lived there from January to April of 2024, and had no income?

If you had no income during the time that you were a Missouri resident, then you would not need to file a Missouri tax return.  If you did have income, then you would file a part-year resident return for Missouri.

Take a look at the answer under the question 'Am I required to file a Missouri return?' at the following link for more information:

Individual Income Tax FAQs - Missouri 
 

You enter your resident state as Kansas.  Since you did not earn any income while in Missouri, when asked if your lived in any other states answer NO.  Where asked if you made money in any other states answer NO.