I see the potential. I've done something like this in the past, so I have some suggestions that I've learned:
- Tone down the sky / moon light
- Tone down the ambient lighting in the foreground
- Tone down the captain's eyes
- Increase shades overall
- The giant horny toed lizard should be more mountain shaped and light shouldn't reach that high
- The held character's left arm is pushing away too far for the similar arm length of the taller one
- Increase detail of the taller figure's eyes and head textures (I couldn't tell what it was for five minutes)
Overall ideas: You can emphasize the Captain's conversation, the beam coming from the giant's mouth, or the held figure; but not all of those at the same time. Two of those need a decrease in importance.
I like the theme of a damsel in distress, like the final scenes of like King Kong. Nice idea! I hope to see a revisit of this work.

Amazing feedback fella! i was asking recently what is usually wrong with my renders and comments like this are gold worthy! thanks you <3