I would’ve gone with editing the skeleton in blender. make sure that what you have is a model in tpose and not just an animation of the model going into tpose, but it’s probably fine if it went through mixamo?
that has to do with the model in the viewer when you preview the animation.
for example I had ybot, so the animations were created related to it. if I changed that, the new animations downloaded would be different.
when you download an animation, you can do so without a model. what determines the starting pose is the skeleton.
I recommend using an addon to add root bones to the animations, as mixamo skeletons don’t take this into account but will be needed for achieving root motion, which all mixamo animations need.
first add a root bone to your model and export it, then (in a new file) use the addon to import all the animations in fbx, this should add a root bone and transfer the animations, and delete all skeletons but one. it’s a good idea to have at least one mesh in one of the files so that the export is correct.
you can also import multiple fbx and delete all skeletons but one. this is recommended for idle animations, while the addon is used for animations that move like walking or running.
then you can export the animations into two files, one for moving and one for idle animations.
in godot, import the files as animation libraries, and add them to the animationplayer of your character.
you also have to assign a skeleton profile humanoid to your animation and model files and assign the correct bones for hands.