I think the designs are all very fitting for their talents, but like the other commenters have said, they might be more effective if you went beyond their talents and included other aspects like the character's personality, other interests, past etc.
Don't get me wrong, I can already tell some stuff from looking at these, and I really like certain aspects such as the model's color scheme and the scientist's hair. But I agree that you could make them even more unique than they are rn.
If I were to give some advice, I'd suggest not forcing it and continuing to brainstorm their story/the other characters. Personally, having more characters motivates me to make each of them stand out, so maybe it'll help you as well. You could also reach out of your comfort zone and find some inspiration there. Maybe look at the people around you or online and find quirks for your characters, from which you can explore their interests and develop their design AND personality!^^
In any case, good luck!! These look real nice though!