Congratulation On Ghadir Feast

Today is the most important feast of Shiites. About 1400 years ago, the prophet Mohammad (PBUH) introduced Ali (AS) as the first Imam to Muslims in his farewell pilgrimage. The event was occurred in the return path from pilgrimage (Hajjatul-Wada) in a place called “Ghadir e Khom“:
In Ghadir, the Prophet (PBUH) held up the hand of ‘Ali and said:

“For whoever I am his Leader (mawla), ‘Ali is his Leader (mawla).”

After his speech, the Messenger of Allah [PBUH] asked everybody to give the oath of allegiance to ‘Ali [as] and congratulate him. Among those who did so was ‘Umar b. al-Khattab, who said: “Well done Ibn Abi Talib! Today you became the Leader (mawla) of all believing men and women.”
It is interesting to know, about ۷۰ days after this day, the Prophet went to the mercy of God and some ambitious people forgotten their oath and select Abubakr as leader of the Muslims and a new branch of Muslims was formed known as Sunni. They do not believe in Imam (Ali and his sons) as innocent people that can show the right path to Allah and truly interpret Qoran, and say that we use our wisdom and find the right path. They say Qoran is sufficient itself and we do not require Imam to interpret it.
But it is more interesting to know that they still expect Imam Mahdi (AJ) to be appear as their Imam!
The event of Ghadir is so clear that no one can deny it. But Sunny people interpret the word “mawla” as “friend” and believe that the Prophet said please like Ali and his sons. And I tell that you can find the truth if you want!
In my opinion its so ridiculous to believe in Mahdi (AJ) as a son of Fatemah (sa) and Ali (as) but don’t believe in Ali and his sons as Imams of the ummah.