Just like Mahā-Viṣṇu. Mahā-Viṣṇu is expansion of the expansion. The direct expansion is Baladeva. The next expansion is Saṅkarṣaṇa. The next expansion is the catur-vyūha. In this way, Viṣṇu, Mahā-Viṣṇu, is expansion of the expansion, kalā. Yasyaika-niśvasita-kālam athāvalambya jīvanti loma-vilajā jagad-aṇḍa-nāthāḥ (Bs. 5.48). Yasya kalā-viśeṣaḥ. Kalā means expansion of the expansion. That Mahā-Viṣṇu is kalā of Kṛṣṇa. Govindam ādi-puruṣaṁ tam ahaṁ bhajāmi **.
So not necessarily all appearances of Kṛṣṇa is direct or He, Himself. There are expansions and expansion of the expansion. That is clearly explained. Ete ca aṁśa-kalāḥ. Some of them are direct, some of them are indirect. But this word Kṛṣṇa is, kṛṣṇas tu, He is but the Supreme Person. Bhagavān svayam, the Supreme Personality of Godhead.