Very good job on your first game. Some tiny suggestions:
1. Sometimes the same word spawns twice in a row which can cause you to shoot twice at the same enemy if you're fast. Maybe do check to ensure you don't have duplicate words on the screen.
2. The text under the enemies is rendered a bit blurry. I assume the cause is floating point coordinates that cause the pixels to be interpolated which doesn't go well with pixel graphics. You could try rounding the coordinates to integers before they're rendered.
Godot might have a built-in feature to fix that. The term "GPU pixel snap" came up on a short Google search. Maybe that helps.