ANSWER: You have asked a good question regarding whether it was an angel or some other being who took the time to wrestle Jacob all night long. Although not many Christians know the answer to this question, the Bible is quite clear regarding the identity of the individual.
Unfortunately, too many believers ignore the Old Testament other than for a few favorite 'tales' – David versus Goliath, Adam and Eve, Cain and Abel, and so on. Not too many people have taken the time to understand the real truth contained in God's word, especially concerning the patriarchs like Jacob and his unique wrestling match.
Jacob was the son of Isaac and grandson of Abraham. The story begins with him traveling from his home to that of his mother's brother, Laban, to find a wife. Although he sought to marry only one woman, he ended up with two wives, as Laban tricked him into marrying his oldest daughter, Leah, when he actually meant to marry her younger sister Rachel. After working for Laban seven (7) years for each woman, Jacob decides to return to the home of his father Isaac.
Jacob, on the way back, sends his sons and wives across the ford (a shallow area where one could cross without too much difficulty) in the river Jabbok but he remained alone on the other side. Then, the Bible says, some seemingly unknown person began to wrestle with him all night long.
And Jacob was left alone. And a Man wrestled there with him until the breaking of the day. And when the Man saw that He did not prevail against him, He touched the hollow of his thigh . . . And He (the mysterious person who tussled with him) said, "Let Me go, for the day breaks."
And He (the mysterious person) said to him, "What is your name?" And he said, "Jacob." And He said, "Your name shall no longer be called Jacob, but Israel; for you have striven with God and with men, and have prevailed." . . . And He blessed him there (Genesis 32:24 - 29, HBFV throughout).
The man who would be renamed Israel, by himself, wrestled with someone who he initially thought was just another man. When his opponent saw that he would not win, he touched his hip so that it wrenched it out of place. To this day, the Israelites do not eat the tendon attached to the socket of the hip because of what happened. Although the man pleaded to be let go, he was not until he gave a blessing.
From the context and background of this story, we learn that the Hebrew name translated as Jacob means 'one who supplants.' He had stolen the birthright blessing from his older twin Esau, but Esau had already sold his physical birthright to him. Since God knew this was going to happen (Genesis 25:23) and He approved (Malachi 1:1 - 4 quoted by Paul in Romans 9:13), He got Jacob to tell Him his name during the wrestling match (verse 27) and then changed it to Israel (the Hebrew word which means 'to have power, as a prince'), thus removing the title 'one who supplants.'
As we read, the scripture does not say that the being who wanted to wrestle was an 'angel' but a 'man.' Although the man does not give his name, Jacob understood that he had struggled with God, for he is quoted as stating "For I have seen God face to face, and my life is preserved" (Genesis 32:30).
Because of all of the above, many believe the person who fought and wrestled with Jacob was not an angel but the member of the Godhead who became the Son. He was the same one who had appeared to both Abraham (Genesis 12:7, 17:1, 18:1) and Isaac (Genesis 26:1, 24) in the form of a 'man.' He later would be known, after being born through a human, as Jesus Christ.