Answer:
I was was before was was was.
small land in water.
I smell like blue paint pours like green paint and I look like a red truck.
You use a knife to slice my head and weep beside me when I am dead.
I can swim but never get wet. I can run but never get tired. I follow you everywhere but never say a word.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.