What effect do the word”heavy” and “big” have in the first stanza of my first memory

you do this because a real teammate puts the team first

the anwser is went creeping down the river again, across the wide lonely marshes to the sea.

i longed to go with them out into the world to seek my fortune in foreign lands—africa, india, china and peru!

and, dreaming of the lands i had never seen, i'd sit on there, watching till they were out of sight.