i think it'd be better to see the art it its native resolution to critique? idk
i mostly have problems with colors and style inconsistency. the blue haired dude is shaded with high contrast shadows and imo looks the best of all the assets. everything else looks flat due to either not strong enough contrast or weak shading .
aside from that id go for a few overall color tweaks playing with hues and values to give everything a more unified style. it has potential but it just looks all over the place stylistically. you want the colors of everything to pull the overall atmosphere together.
lastly the portrait of the woman speaking really would benefit from adding depth to the face so it doesnt look flat, and especially to giving shadows to the hair to place it on the head so it doesnt look like floating hair
that said, could you explain what atmosphere youre going for/
it kinda has mixed elements of cute and serious. the characters and enemies look a little chibi like and the rest looks a little less cute