The redemption of captives held for ransom takes precedence over sustaining the poor and clothing them. You do not find a mitzvah greater than the redemption of captives, for captivity is in the same category as famine, drought, or exposure, and one stands in danger to one's life. One who averts his eyes from redeeming [the captive] transgresses [the commandment], (Deut. 15:7) Do not harden your heart and shut your hand, and (Lev. 19:16) Do not stand upon the blood of your neighbor, and (Lev. 25:53) He shall not rule ruthlessly over him in your sight, and nullifies the commandment (Deut. 15:8) You must open your hand, and the commandment, (Lev. 25:36) Let him live by your side as your kinsman, and (Lev. 19:18) Love your fellow as yourself, and (Proverbs 24:11) If you refrained from rescuing those taken off to death, [those condemned to slaughter--if you say, "We knew nothing of it," surely He who fathoms hearts will discern], and many such sayings. You cannot find a greater mitzvah than the redemption of captives.
The Gemara explains: As a dilemma was raised before the Sages: What is the halakha with regard to whether a son may let blood for his father? Is he liable for wounding his father? Rav Mattana says that it is written: “And you shall love your neighbor as yourself” (Leviticus 19:18); just as one would want others to heal him when the need arises, one must heal others when the need arises.
תשובה הרשב"א ז"ל העלה בתשובת שאלה שהוא בכלל ולמד אותה מק"ו דשור וחמור דאי משום צערא דבעלי חיים כ"ש צערא דישראל גופיה ... ובאדם לא אמרו צער האדם לפי שהוא בעל שכל ולא היה לו לטעון עצמו יתר מן הראוי לו דמהאי טעמא אמרינן שהטוען על האדם יותר מן הראוי לו והוזק פטור דכיון שהוא בעל שכל היה לו להשליך המשא מעליו מה שאין כן בטוען על הבהמה ומ"מ מודה אני שהוא בכלל ג"ח בכלל ואהבת לרעך כמוך אבל שיהיה בכלל עשה דטעונה ופריקה לא מסתברא לי.
Question: Does this mitzvah apply to humans as well?
Answer: The Rashba asks this very question, and learns it out from an a fortiori argument: a donkey or a bull, if the mitzvah is about relieving pain from an animal (tzar baalei chaim), then all the more so should it apply to a Jewish person themselves!
I disagree: we do not apply the category of tzaar to people, since people have intelligence, and such a person should not have burdened themselves with weight that they would not be able to carry!
We know this from the halacha that if a person [contracts with another] to carry items, if the items are too heavy and the carrier is injured, the contractor is not obligated - for the carrier should have refused to carry more than he can. But an animal cannot refuse...
However, it is still correct to help the person, out of the broader obligation of gemilut chassadim, and the mitzvah of v'ahavta l'reiecha kamocha. But under the obligation of "lightening the burden", the person would not seem to be obligated.