not quite --
before the Council of Jerusalem in 50 AD, there were disputes about the Law. Paul opposed "works of the Law", as being necessary for Salvation. Jews were wroth. In Rome, and Greece (Acts 17), these disputes led to riots, causing emperor Claudius to expel all Jews (including Jewish Christians) from Rome (Acts 18). Paul wrote
Galatians, and James wrote
James, about this time.
But, the Church convened the Council of Jerusalem; Bishop James of Jerusalem judged the dispute; and the whole Church obeyed his judgement. Thereafter, there did
not remain "different denominations".
THE Church no longer has such singular authority -- today, there do remain different denominations.
Although, on second thought, "works righteousness" was a central issue, one the "main & plain" things as you said; perhaps different local Church branches always have had slightly different localized customs, which need not cause conflicts.
does it not seem, sometimes, as if people are
want to disagree ?
That's a good way to considered yourself. But due to sin, in which we are still affected by, denominations arose from disagreements in theology. The main thing is agreement on the main and plain things, the essential Christian doctrines and not the secondary issues. PS. Disagreements in the body of Christ is nothing new, read Acts 15:29, Barnabas and Paul got into it. Worship and the overall function of a local church goes smoother IMO, when even most agree with also with the secondary issues.