The Hebrew verb here indicates first-person common plural.
To see the general conjugation chart for this verb,[CLICK HERE], or for the specific chart with the form of the verb that occurs in Genesis 1:26 highlighted, [CLICK HERE].
On the chart for this verb, which means "to do, to make, to create", notice that "we did" would be "עָשִׂינוּ"; whereas "I did" would be "עָשִׂיתִי". The actual word used in the verse, which is the future tense form, is "נַֽעֲשֶׂ֥ה" -- as is highlighted in the chart at the second link provided above.
This apparent contradiction to all other places in scripture where the Hebrew verbs used with "elohim" when referencing the true God are found in singular construction can be explained in one of several ways.
Importantly, the word "elohim" does not mean "God" in Hebrew. It has a much broader meaning than this. It can mean God/god/gods (and usually does), but is not limited to only this. In Psalm 82:6, for example, the word applies to people.
I have said, Ye are gods [Hebrew: "elohim"]; and all of you are children of the most
High. (Psalm 82:6, KJV)
Lest anyone think this to be a mistranslation, Jesus himself affirmed it, as is translated to "theos" (God) in Greek.
Jesus answered them, Is it not written in your law, I said, Ye are
gods [Greek: "theoi" (plural of "theos")]? (John 10:34, KJV)
The word "elohim" is also used to reference judges in the Mosaic law.
For all manner of trespass, whether it be for ox, for ass, for sheep,
for raiment, or for any manner of lost thing which another challengeth
to be his, the cause of both parties shall come before the judges
[Hebrew: "ha-elohim"]; and whom the judges shall condemn, he shall
pay double unto his neighbor. (Exodus 22:9, KJV)
It is also noteworthy that in this verse in Exodus, the word "elohim" is prefaced by the definite article in Hebrew, like "the" in English. This is notable because in Hebrew a name is never prefixed by the definite article. Therefore, while many scholars (not all) attempt to claim that "elohim" is God's name, its grammatical usage does not agree with this conclusion. Here it is clearly used as a common noun, not a definite (proper) noun.
Returning to Genesis 1:26, the word "elohim" cannot reasonably be limited to God alone without violating other Hebrew passages. The question then becomes, "Whom is God including along with Himself?"
I would submit God is including the angels of heaven in His statement.
For thou hast made him a little lower than the angels [Hebrew: "elohim"], and hast
crowned him with glory and honour. (Psalm 8:5, KJV)
The heavenly angels have been very active in God's behalf toward restoring in man the image of God lost when Adam sinned. They are participating with God and with Christ in recreating man in God's image. This text is not merely to be seen as historical: note the future tense of the Hebrew verb--unlike the past tense used elsewhere throughout the creation account. This text is prophetic. And that is what makes this a special verse.