Consider 1:1 vs Group Messaging
When my team worked on the left vs staggered approach to message bubble alignment we did some internal A/B tests to see which performed better and the majority of people found a staggered approach easier to interpret.
Also I think it gives clear separation between yours vs theirs, but this alone wasn't enough to differentiate, so we included alternate colours for the messages, this also helped visually identify who was who.
Consider 1:1 conversations for example this may work well, but for group messaging we aligned all other parties to one side and 'you' to the other.
Slack have these all to the left side and the one colour approach which still works great, however I find this approach takes extra concentration from the user to identify conversation origins.
Slack also try to overcome this via avatars and bold usernames with chunking of messages delivered without reply.