I feel that original Buddha's teaching may be selflessness (egolessness) based on unconditional self-love. ("self" of selflessness means ego (separate self) and "self" of unconditional self-love means true self (non-separate self).) Therefore, Buddha's selflessness (egolessness) may not be based on emptiness (interdependence). Because emptiness (interdependence) can explain the absence of separate self (ego) but can not explain unconditional self-love (existence of true self). In this sense, I feel that the Four Noble Truths (the first wheel of dharma which explains "selflessness") were created by Buddha, but the Heart Sutra (the second wheel of dharma which explains "emptiness") may not be created by Buddha.
By the way, I have a question. If you can choose only one of the two, which will you choose, emptiness (interdependence) or unconditional self-love? I understand that these two can go together if both sides are non-separate self. However, if either side has too strong ego (separate self), these two can not go together. I mean that one side (ego) can accept emptiness but can't accept unconditional self-love. Therefore, the other side (true self) needs to choose either one.
Bodhi Tree in Bodhgaya