Is he interested or just nice?

If a man helps me with a complex task out of our work circle (fin modelling) and wants to continue helping me (he’s not an expert in the topic also, looks like tries to make something up to help me), went out with me to give advise even being very busy, tries to initiate small talk when we meet in hall, looks into my eyes warmly, does it mean he likes me?
Tho he hasn’t yet made more obvious moves, does it mean I overthink everything or he’s unsure about my feelings to be more confident?
What should I do to show my mutual interest?
Is he interested or just nice?
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