Recently, I’ve been feeling anxious about my career.

I can't imagine how my works led to the improvement of products and someone's health.

I can't imagine how my works ledads to the improvement of products and someonor people's health.

Personally, "someone" isn't the best choice because I don't think this sentence has a particular "someone" in mind or is only limited to one person, so making it plural sounds better. If you did intend to refer to "not being able to imagine how an individual person's health could be improved by your work" then I would go with Profitendieu's correction.

Also, if you are thinking specifically about the people buying these products I might say: "I can't imagine how my work leads to the improvement of products and consumers' health."

Recently, I have feelt anxious about my career.

Or: "have been feeling." I would use the present perfect because we are describing something continuing from the (recent) past.

I've only checked someone's documents oin which analytical data were summarized, and attended some meaningless meetings about how to collaborate with a local mascot character for an advertisement.

- To make this more concise: "some documents summarizing analytical data" ("someone" is already understood)
- "Collaborate with a local mascot character" doesn't seem right to me because one really collaborates with the team behind the character. However, I think it could be fine in context, since we say things like "They did a collaboration with Hello Kitty."

I can't imagine how my works ledads to the improvement of products and of someone's health.

Or: "could lead"