Here is a super simple program that is free that I have used for years.
It's fast, free and easy.
I set it up on automatic. Now when I want to resize my pics, I just right click and choose MAKE THUMBNAIL.
It automatically makes the thumbnail to my predetermined size and deposits it in a file named THUMBNAIL. This way I still have both the original and the new smaller one. I then go to the THUMBNAIL file and insert the pic where I want it.
For instance my normal pic is 3264 x 2448, after right clicking MAKE THUMBNAIL, the new pic is 600 x 450 (my predetermined specs allow for the largest side to be 600)
It is now residing in the THUMBNAIL folder with the same name except THUMBNAIL has been tacked on the end of it. That way the original and the thumbnail have 2 different names.
At any time I can open up the original program and change all the configurations for a custom job, but it has this option to preconfigure everything and just use the right click to do it all automatically to your prior specifications. I think I have used this program since the turn of the century and it just keeps on purring.
EASY THUMBNAILS by Fookes Software
https://www.fookes.com/easy-thumbnails
;D
I don't think it gets any easier than this. 8)