Not bad @Diso_, but we want our cuts to be cropped much closer to the head, leaving no more than 2-3 pixels above and beneath the head, and also to be much sharper than that. This thread contains guidelines for what we're looking for in our cuts in terms of dimensions, snow, collars, face orientation etc. and video tutorials for each element.

Can you provide us with the original source images without the background removed for the cuts I've rejected, so that we can cut them accordingly?

If you want to give them another go yourself, I would recommend using remove.bg, which is a free online tool which removes the background to an excellent standard, for free and almost instantly.

Here's a couple of videos on how to use it, one when combined with Photoshop and another using photopea.com, which is a free online app so close to Photoshop that it has the same shortcuts, layout and icons.

If you don't have Photoshop, photopea.com is the tool I would recommend to use to tweak the draft cut produced by remove.bg. It's more powerful and versatile than GIMP and other similar tools.