That refers primarily to people or things; which refers primarily to things, and who refers primarily to people. Some authorities insist who/whom be used when making reference to people, but others, such as the Merriam-Webster dictionary, write that such prescriptions are “without foundation” and use of that in such positions is common and “entirely standard”.[2] Hence, one sees both “he is the man who invented the telephone” and “he is the man that invented the telephone.”
https://en.m.wiktionary.org/wiki/that