plow
犁 centers on the agricultural tool and action of plowing: turning over soil with a plow.
犁 combines 利 (sharp, profit) and 牛 (cow), suggesting a sharp tool pulled by an ox to plow fields. The exact historical development is uncertain, but the component combination fits the meaning well.
The top 利 suggests a sharp blade, and the bottom 牛 is an ox. Picture an ox pulling a sharp plow through the soil.
For リ, imagine the plow leaving a neat line in the field: the word 'line' sounds like リ, and the plow creates straight lines.