I mean it's difficult to gauge who is working class or what the definition is/was especially with 5 minutes looking at online profiles but:

John McDonnell's father was a bus driver, and he left school with no qualifications. He held unskilled jobs before going to night school.

Angela Rayner left school as a pregnant teenager with no qualifications, and worked as a council care worker before becoming a union rep.

Rebecca Long-Bailey's father was an Irish docker, and she originally was a pawn shop worker, call centre worker and postwoman before studying as a solicitor

Valerie Vaz's mother worked two jobs to support her family

Jon Trickett spent 12 years as a builder and plumber

David Anderson was a miner and a care worker.

So yeah, before entering politics a lot of Labour's front bench were on minimum wage/unskilled/labouring jobs. Plus a few more are the children of immigrants who came from the commonwealth in the 60s, and would absolutely have been on a "working class level" of household.