How to explain use of "что" when a person is being referred to in songs?

Question

I roughly understand that "кто" is used when referring to a person and "что" when referring to a thing, but I've found at least three examples in songs where this doesn't seem to be the case. I include YouTube links at the exact timestamp where this happens:

"Из вагантов" https://youtu.be/fAHWvUANVCg?t=105s

Если те профессора,
Что студентов учат

"Чиж & Co - Вечная молодость" https://youtu.be/dGsEzJ0S1-E?t=60s

Еще была солистка Леночка
Та, что училась на год младше

"Бумбокс - Та Что" https://youtu.be/9jFOKH3brQc?t=40s

Та, что была со мной, где ты теперь?

It seems this question is related, but the answer is too technical for me to understand if/how it applies to the above examples.

I'm looking for a simple explanation of how to interpret the above lyrics.

Answer 1

Что in this context is a relative pronoun, corresponding to English "who", "that" or "which".

• If those professors that teach the students…

• There also was Lena, the lead singer, who was a grade younger

• You (literally, "that (woman)"), who were with me, where are you now?

This usage is a little bit dated, and a Modern Russian speaker would probably use который ("which") instead of что in these phrases. But in poetry and grand style texts, it's perfectly ok to use it.

Apparently, "which" used to work as a personal relative pronoun in English as well, up until early Modern English. In KJV, the Lord's prayer reads: "Our Father which art in heaven".