As claimed (here) Talmud confirms that there are 613 Commandments in total in the Torah, but can the precept be summarized? The Oral teaching tradition helps us, the Scriptures tries to capture the essence of the mitzvot:
[King] David came and reduced the [613 commandments] to eleven [principles], as it is written [in Psalm 15]:
A Psalm of David. LORD, who shall abide in Your tent? Who shall dwell in Your Holy Mountain?
(1) He who walks uprightly,
(2) and does what is right,
(3) and speaks the truth in his heart.
(4) He who does not slander with his tongue,
(5) nor does evil to his neighbor,
(6) nor takes up a reproach against his neighbor.
(7) In whose eyes a vile person is despised;
(8) but he honors those who fear the LORD.
(9) He who swears to his own hurt, and does not retract.
(10) He who does not put out his money at interest,
(11) nor takes a bribe against the innocent.
He who does these things shall never be moved.
[The prophet] Isaiah came and reduced them to six [principles], as it is written:
(1) He who walks righteously,
(2) and speaks uprightly;
(3) he who despises the gain of oppression,
(4) he who shakes his hands from holding bribes,
(5) he who stops his ears from hearing of blood,
(6) and shuts his eyes from seeing evil;
He shall dwell on high. [Isaiah 33, 15-16]
[The prophet] Micah came and reduced them to three [principles], as it is written:
It has been told you, O man, what is good, and what the LORD requires of you:
(1) only to do justice,
(2) and to love mercy,
(3) and to walk humbly with your GOD [Micah 6, 8]
Again came [the prophet] Isaiah and reduced them to two [principles], as it is said:
Thus says the LORD,
(1) Keep justice,
(2) and do righteousness [Isaiah 56, 1]
[The prophet] Amos came and reduced them to one [principle], as it is said:
For thus says the LORD to the house of Israel,
(1) Seek Me, and you shall live [Amos 5, 4]
But it is [the prophet] Habakuk who came and based them all on one [principle], as it is said:
(1) But the righteous shall live by his faith. [Hab 2, 4]
The Master Jesus finalize the doctrine remain connected to the tradition. Theology and study of Torah are not complicated, but comprehensible even for a child, and the Messiah summarizes all the Scriptures in two simple Laws to follow to obtain the Kingdom of GOD.
The only 2 Commandments that really matter: Love GOD (cherish Love) and love your neighbor (those who are close to you)
28 And one of the scribes came up and heard them disputing with one another, and seeing that he answered them well, asked him, “Which commandment is the first of all?”
29 Jesus answered, “The first is, ‘Hear, O Israel: The LORD our GOD, the LORD is one;
30 and you shall love the LORD your GOD with all your heart, and with all your soul, and with all your mind, and with all your strength.’
31 The second is this, ‘You shall love your neighbor as yourself.’ There is no other commandment greater than these.”
32 And the scribe said to him, “You are right, teacher; you have truly said that he is one, and there is no other but he;
33 and to love him with all the heart, and with all the understanding, and with all the strength, and to love one’s neighbor as oneself, is much more than all whole burnt offerings and sacrifices.”
34 And when Jesus saw that he answered wisely, he said to him, “You are not far from the Kingdom of GOD.” And after that no one dared to ask him any question.
(Gospel according to Mark 12, 28-34)