A mushroom is a weird example for empathy for a few reasons. First, the part you eat is really just the "fruit" or reproductive part of the mushroom that only lasts for a short time before withering away. Second, mushrooms very happily eat you after you die, hell, even before you die you're covered in all kinds of unicellular fungi which are actively trying to eat you.
More to your philosophical point, the beauty of life is always transitory. Life begins, blooms, withers and dies but also passes on the small immortal spark that it all came from to the next generation so it can repeat the cycle. I'm against cruelty to animals but I also recognize that eating them is part of life and that it is possible for us as conscious beings to give them a better life than they would have in the wild and then kill and eat them and I'm ok with that. I don't want to live in a world where all cattle or pigs are reduced to a few wild populations scrabbling for survival against the elements and disease while being occasionally mauled and devoured alive and screaming by wolves and other predators. To me that's more immoral than a properly maintained herd that is sheltered, fed and given medical attention and then slaughtered as painlessly as we can manage.
Before all y'all reply with "factory farming", yes I'm aware of its prevalence but that just means we should be working to reduce that type of treatment, not eliminating raising animals for meat entirely.
