First sort on the organism column (and save the part with "human") as text (comma or tab delimited format) from Excel.

Take inspiration from this post and try a few things out: A: Split single columm into multiple colums

You can also use awk with correct delimiter, along with a checking if/else construct as an alternative.

Note: Someone will spoil your learning by posting a ready-made solution before long but resist the urge to use that solution :)