Shalom and thank you for your question! You wish to understand why the Torah states “Let US make man,” which seemingly indicates that there could be, G-d forbid, more than one deity. Additionally, you are wondering why there are other references to G-d in the Torah that are in plural form.
Firstly it is worthwhile taking note of the fact that the Five Books of Moses and the writings of King Solomon and of the Prophets cannot be understood without the body of Oral law that was transmitted from Moses to Joshua and from him to the subsequent spiritual leaders of the Jewish people throughout the generations. Where did Moses receive it from? From G-d of course. Both the Written and the Oral law are Divine in origin. The Oral law is indispensable in knowing how to understand and practice what is written in the Torah. It includes the Talmud and commentaries as well as the whole body of Jewish law.
Your question was asked by some of the most famous Torah scholars and commentators.
The Abarbanel (medieval Jewish scholar, who was also a statesman and philosopher in Portugal,) explains that the statement “Let us make man” indicates that man was created by G-d with great deliberation and wisdom, since the accounts of other creations are not prefaced with extra terms. The text merely states “Let there be light” for example, without any introductory statement.
The Targum Yonasan helps us understand the passage “Let us make man in our image, after our likeness,” as meaning that G-d is addressing the ministering angels that had been created on the second day of Creation.
The Midrash (interpretation by the Talmudic Sages,) tells us that when Moses wrote the Torah and came to this passage, he said: “Sovereign of the Universe, Why do you thus furnish a pretext for heretics to maintain that there is a plurality of Divinities?” G-d answered “Write! Whoever wishes to err will err… Instead, let them learn from their Creator who created all, yet when He came to create Man He took counsel with the ministering angels “.
This is a lesson in humility. When important decisions have to be made, or new projects undertaken, it is wise to learn from G-d’s example and take counsel. Also, if a person is sincerely searching for truth, he/she will eventually find it regardless of its apparent hiddenness.
Another example of referring to G-d in the plural is the title ‘Elokim.’ (Spelled E-l-o-h-i-m but when used in conversation we don’t spell it completely out of respect for its holiness.) Literally it means G-d in plural. Here however, the plurality does not refer to G-d but to the creation, which is a conglomerate of many creatures and features, all of which were created and are constantly RE-created by G-d. You see G-d has many names and each name describes a different aspect of Divinity. The name ‘Elokim’ describes the aspect of nature, which is a plurality of created beings with their behaviors, while the name ‘Havaya’ (the Tetragramaton,) refers to the transcendental aspect of G-d. G-d is infinite and not limited by the dimensions of time, space, or emotion. Hebrew letters have numerical values, and the numerical value of the word ‘Elokim’ in Hebrew is the same as ‘haTeva,’ which means nature. G-d created nature, the laws of nature, and miracles- which are a digression from nature. At the beginning of Creation G-d made a condition with the waters that they would digress from their nature and split when the Jews would leave Egypt. At that time with that miracle, G-dliness was more revealed and that was a manifestation of the transcendental aspect of G-dliness as expressed in the name ‘Havaya,’ rather than the ‘Elokim’ aspect.
Perhaps it is not a coincidence that in many languages the custom became to address royalty and important people in the plural, even when addressing a single person. In some languages the plural prefix is used whenever addressing someone older or with an important position.
