My humble contribution means helping others as much as I can. Sentence: We ordinary people donate money and materials just to do our little bit, so that everyone fighting in the front line can at least be safer and have some protection, and don't have to worry about things other than the epidemic. The difference between "meager strength" and "meager strength" means that strength and ability are few and thin; "Small strength" means small strength, small strength and insignificant strength.
The usage of "meager strength" is wider; "Modesty" is a kind of modest speech, which is mostly used for self-modesty, meaning to do one's best. "meager strength" refers to objective facts; "Small efforts" means modesty, which means doing one's bit to help others. In fact, it may have great ability.