26 - Levites who were gatekeepers, treasurers and judges are listed.
27 - Military divisions: there were 12, one for each month, and 24,000 soldiers to each. They do not appear to be by tribe, which was new since the time of the judges. Tribal leaders are given next, so this identity isn't gone. Stewards of the king's flocks, fields, vineyards and treasuries are listed.
28 - all this organization has been buildup to building the temple. David again charges Israel and Solomon to build it, after asserting that God made Judah and David leader of Israel. He presents detailed plans for the temple. David has prepared all the material and organized manpower. All that's left for Solomon is to do it.
29 - David publicly gives gold and silver to the temple work and calls on Israel to give, and they do. David thanks God and calls on Israel to worship Him, and they do.
Solomon is installed as king and David dies.
How this is about Jesus
There is a parallel with Jesus' life. Building His church doesn't really begin until after His death. Note the future tense in "I will build My church" (Matthew 16:18). But He organizes His people into 12 divisions/apostles to prepare for it.
Lead by example in worship and giving, as David does here.
The military appears to be a "serve 1 month out of the year" reserve style, rather than a standing army. Hm...
Organization has a larger purpose than just feeling good about yourself. What is the purpose of any and every nation? To glorify and aggrandize itself? NO. To build and beautify a place for the worship of God, and direct all its people to do so.