The convoy was being used to transport Hamas militants, masquerading as humanitarian aid workers (a war crime fyi). The attack targeted (and struck) only the militants.
Claiming this was an attack on a humanitarian convoy and that some random people were hit is highly misleading
https://armenpress.am/en/article/1198626
https://www.timesofisrael.com/liveblog_entry/idf-says-it-struck-gunmen-who-hijacked-aid-convoy-in-southern-gaza/
The Guardian is an untrustworthy biased POS.