1. Little kids DO see race. They simply don't have the vocabulary to discuss it, and don't necessarily need to discuss it.
2. Little kids are behaviorally influenced. Enough bad experiences with another race, or just one really bad experience, will result in racist ideas.
3. People are self-sorting. Just as boys and girls eventually stop playing together, kids with different cultural identities often drift apart.
4. My simple solution would have four steps: A) teach the imago dei, B) teach Romans 3:23, C) teach unlimited atonement or at least Revelation 7:9 and D) teach the golden rule.