Response: Yes, there's more! In fact, striving for perfection is not even a component of Christianity.
If you are trying to be perfect, please stop. You're making yourself miserable, and there's a decent chance you're making those around you miserable as well.
If you're thinking of Matthew 5:48, "Be perfect as your heavenly Father is perfect," then let me point you toward the CEB translation.
Therefore, just as your heavenly Father is complete in showing love to everyone, so also you must be complete.
The word typically translated as "perfect" (Greek: telos) can also mean complete, full, or mature. Matthew 5:43-48 are all about God's enemy-including love. God shows kindness to both the righteous and the unrighteous. In the same way, we are not to hate our enemies but love them.
As for us, perfection is a treacherous goal that, as I said, will only make us miserable. Rather, "love your neighbor as yourself" sums everything up pretty well.
Loving yourself—showing yourself bottomless compassion and kindness—is crucial. Perfectionism will smash that compassion pretty quickly.
Loving others in the way that would want to receive love is a pretty good place to start building ethics.
If by avoiding sin you mean avoiding arbitrary rules that make God angry, then, no, that's not it. If by sin you mean whatever harms people and creation, then yeah, don't do that.
I also think knowing and being known by God (being open to mysticism, discovering God in nature, worship, friendship, and pleasure) is a crucial cornerstone of Christianity as well.
This is what Jesus meant by "Gospel" or good news: the Kingdom (rule, reign, commonwealth) of God has arrived. What God wants for creation is coming true through us, God's people. And what God wants for us is to enjoy creation (including people!) and care for it.
St. Paul, who people mistake for an old stick in the mud, said it best:
Why do you submit to rules and regulations? “Don’t handle!” “Don’t taste!” “Don’t touch!” All these things cease to exist when they are used. Such rules are human commandments and teachings. They look like they are wise with this self-made religion and their self-denial by the harsh treatment of the body, but they are no help." (Colossians 2:20-23)