I think it's about someone (not necessarily Alex) having suicidal thoughts,"Running from lions never felt like such a mistake", the lions are sort of a metaphor for death, 'sort of' because they are a cause of death but not his/hers. They are saying they are not at the point where they are seriously considering taking their own life, but if an opportunity to die arose they wouldn't deny it, like if a car was coming for them they wouldn't move. The first verse is about how they mess everything up and won't be missed. The chorus is about the future that they could have if they hold on to life and their excitement for what's to come.
I think it's about someone (not necessarily Alex) having suicidal thoughts,"Running from lions never felt like such a mistake", the lions are sort of a metaphor for death, 'sort of' because they are a cause of death but not his/hers. They are saying they are not at the point where they are seriously considering taking their own life, but if an opportunity to die arose they wouldn't deny it, like if a car was coming for them they wouldn't move. The first verse is about how they mess everything up and won't be missed. The chorus is about the future that they could have if they hold on to life and their excitement for what's to come.