Let's say that someone is a good person and donates to charity often or whatever, does he have a chance of going to Jannah?
Firstly, only Allah SWT knows who is going to Paradise and who is going to Hellfire.
Consider it this way: What is the purpose of our creation? And what is the path to Jannah?
Allah SWT says in the Quran, in Chapter 51, Verse 56, the following: “And I did not create the jinn and mankind except to worship Me.”
Additionally, in Chapter 2, Verse 82, He says, “But they who believe and do righteous deeds - those are the companions of Paradise; they will abide therein eternally.”
Chapter 3, Verse 124 states, “They believe in Allah and the Last Day, and they enjoin what is right and forbid what is wrong and hasten to good deeds. And those are among the righteous.”
In each of these instances, the reward is mentioned for those who believe FIRST and then do good works; one has to believe in God as the only one God and the only one to be worshipped for this reward. The reward of Paradis is for those who do good for the sake of Allah SWT. Those who do not believe may do it out of charity (and others insincere motivations ) but their intentions do not involve the remembrance of God.
Now. The question is, as a “Hindu,” does one live according to these requirements?
Acknowledging the existence of God is not merely enough, as we are entirely at His mercy and must show gratitude. Part of this entails praising and worshipping him. Yes, it is also an attribute of a believer to be a good person and charitable, and not every good person is a believer. To only be a good person is not sufficient as one is then rejecting the fact that Allah SWT is The One and The Lord of the Heavens and the Earth, the One who created everything.
And Allah SWT knows best.