I haven't lived before. I don't believe anyone else has. BUT, if someone says they have that's on them, I'll not argue with them.
Have we lived before?
There is no evidence that supports us having more than the current life we have.
So, I do not believe we have lived in another life before.
Yes, I believe I've lived many lives and will live many more !
No, no one has live before, but the bible does speak of being able to live forever at John 17:3,"This means everlasting life, their coming to know you,the only true God,and the one whom you sent,Jesus Christ."