Is continuing to help others—despite the bitterness of the experience, the denial of some, and not seeing the effect of that in life—pleasing to Allah Almighty, and is not seeing the effect good or evil, and should one stop doing that?

Helping and doing good to others is a great act of faith. One might become frustrated if they do not see the effect of their good deeds in the form of people's gratitude or worldly reward. Nevertheless, Allah rewards the doer of good in this world and the Hereafter. The good outcome might be the دفع of an affliction, the attainment of blessings that the doer of good does not perceive, or the full reservation of the reward for the Day of Judgment. For true giving is for Allah alone. Good deeds should be done with balance and moderation, without excess that harms oneself or other duties.