The last two proberbs shouldn’t be taken literally.
Lions do eat grass sometimes to diet and to ease digestion.
Assuming lions don’t eat grass for any reason at all and they suddenly begins to eat it because they couldn’t find meat to eat, how humiliating that could be.
However, (still assuming lions don’t eat grass at all) instead of the lion to die out of hunger when there is no meat, it had better eat whatever that is available to sustain life. Same to human, to survive one can do the most humiliating thing.
The last proverb is literally true for some places in the world where problems are not solved until people begin to lose their lives to it. It doesn’t have to be so.