Immaturity. A child. I deal with a forty-eight year-old ex-business partner that does it in every business failing.
We call them a teller
Someone who blames others for their mistakes would have an external locus of control. This means that the responsibility for their actions is outside of them (so they are not responsible). This is also a part of the Fundamental Attribution Error, which states that people tend to attribute their success more to themselves and their failure to others or situational factors.
That person could be described as a "blamer" or "responsibility avoidant." Their behavior might suggest a lack of accountability and a tendency to deflect fault onto others to avoid facing their own actions.
maybeeeeee
accuse
A person who consistently blames themselves for everything may exhibit traits of self-blame or self-criticism. They could also be characterized as having a tendency towards self-guilt or self-condemnation.
A critic
The superior man knows what mistakes he has done and take the blame while the inferior man passes on the blame to others.
a troublemaker?
A person who does things for others may be an assistant or a helper.
This would be an eavesdropper.
An altruist