Nice game, but has some potential for improvement.
I liked the art although I found it a bit inconsistent, different styles and resolutions are mixed. The title screen art was very nice too.
There were a few bugs, although they weren't game breaking so I didn't mind them much. Some textures flickered and some things could be fallen through.
The scale of the world seemed to change quite a bit throughout the game, in particular when entering any of the side worlds.
The music was nice, although a bit repetitive and it didn't seem to loop perfectly.
I think a more detailed story would've been nice to explain why you're on the planet and what the thingies are for.
It was really quite an easy game where I never really got lost or had trouble staying alive. More enemies to fight could've been nice. Simply spamming the attack was a bit too easy.
I also think an explanation of the controls would be good. I didn't understand the blue bar until the end when I accidentally found out about the flying mode.
I didn't really feel that it was a metroidvania because there was no ability gated exploration. Picking up the thingies doesn't give you any abilities.
The spaceship location was a bit weird since it doesn't seem to be where you came from and it was unclear that it was so important.
Overall it was quite enjoyable, good job!