BG Chap 9 - The nature of Kṛṣṇa's form
The ignorant do not know that the human form is Kṛṣṇa’s svarūpa, more attractive and superior to the Mahā-puruṣa lying on the Kāraṇa ocean and other forms as well. Kṛṣṇa’s form is the great lord of Brahman and thus is different from Brahman. Kṛṣṇa’s form is sac-cid-ānanda. It controls everyone and it gives liberation. The human form of Kṛṣṇa is the most exalted state (param bhāvam), viśuddha sattva, a svarūpa of sac cid ānanda. Kṛṣṇa is the Supreme Lord of Brahmā and others and He is not different from His human body. His body is Brahman. Those blinded by material energy can understand this truth only thru the scriptures.
Here Kṛṣṇa confirms that His human form is supreme and later Arjuna calls the four armed form human as well (BG 11.51). Thus it is concluded that Kṛṣṇa’s human form is spiritually fixed as part of Himself. The Viṣṇu Purāṇa says that the supreme Brahman called Kṛṣṇa appeared with human form. The Bhāgavatam says the supreme Brahman in its secret aspect has a human form (SB 7.10.48). Also it is said that Kṛṣṇa assumes a human form in order to express the abundance of His human-like actions. Thus He is called human because He has an eternal human form and because He performs human-like activities. One cannot determine Kṛṣṇa as the supreme or human simply based on His having two or four hands. For instance, Kārtavīrya had a thousand arms. But that does not make him God or more than God. Kṛṣṇa is God because of being the supreme conscious entity and His ability to generate and destroy universes. The Gopāla-Tāpanī confirms that the Lord has two arms eternally.