As per the definition, myth is not a false idea but talks about the psychological situation of people at the particular time.

In that case, is Ramayana and Mahabharat events that really happened according to Hinduism?

As per the definition, a myth is something, which is not necessarily false, but it is usually based on current psychological makeup. It can be true as well in some cases. The job of a myth is to identify a people and connect them to the divine.

With regards to Mahabharata and Ramayana, even the Hindus do not consider these as facts. So usually a myth is not true but it can be since it is not necessarily false. Even historically it is not possible to verify or prove the authenticity of the myths mentioned in these books.