How Does Oracle Handle Multiple Concurrent INSERTs Against One Table
The inserts don't affect each other unless they would have a conflict with unique or primary key constraints. They should be independent. I believe this concurrency issue is one of the reasons why Oracle's sequence is a separate object (cached, surrogate PK generation separated from insert).

In that respect, they operate on the uncommitted table as it is seen to their session. This behavior is described in the stackoverflow post below.

https://stackoverflow.com/questions/3194999/dml-by-multiple-users-commit-scenarios-in-oracle