Using civilians as shield makes more sense for defenders, not for attackers. Civilians makes harder to shell and bomb places. The exception is if attackers force civilians to march in front of their troops, which is not the case apparently.
Russia mined the path they themselves had designated as a humanitarian corridor before. To target civilians. This is reported from Mariupol.
Please, don't come with conjectures about Ukrainians using civilians as a meat shield, this is either utterly bollocks or you need a pretty convincing source for that statement.
Reports? There's video all over the internet. Yesterday I saw a video of a solitary civilian car being lit up by machine gun fire before taking a couple shells. I'm told there were accompanying photos of a dead couple in their 80s, which I didn't look at because I want to sleep at night.