I looked at thoes for my son. Because you (I think) didn't have one with the packaging still on it, you did not know that thoes are for kids that know a bit about how to swim. I think the are a 'Stage 3' which is says, something about being used only on kids that have had some swiming but still need a little help. It does NOT say anywhere (That I saw) on the packaging that it is a life saving device. It does say "use only with adult supervision" (did I spell that right?)
Sounds like you where there and that's good. Just because it "looked safe" and said "Life suit" does not mean it is a "Life SAVING" device.