Saul is the first king of Israel put on the throne after the people complained to Samuel that they wanted a human king like "the other nations" rather than God as their leader and king.
Israel Asks for a King (1 Samuel Chapter 8)
When Samuel grew old, he appointed his sons as Israel’s leaders. 2 The name of his firstborn was Joel and the name of his second was Abijah, and they served at Beersheba. 3 But his sons did not follow his ways. They turned aside after dishonest gain and accepted bribes and perverted justice.
4 So all the elders of Israel gathered together and came to Samuel at Ramah. 5 They said to him, “You are old, and your sons do not follow your ways; now appoint a king to lead[b] us, such as all the other nations have.” 6 But when they said, “Give us a king to lead us,” this displeased Samuel; so he prayed to the Lord. 7 And the Lord told him: “Listen to all that the people are saying to you; it is not you they have rejected, but they have rejected me as their king. 8 As they have done from the day I brought them up out of Egypt until this day, forsaking me and serving other gods, so they are doing to you. 9 Now listen to them; but warn them solemnly and let them know what the king who will reign over them will claim as his rights.” 10 Samuel told all the words of the Lord to the people who were asking him for a king. 11 He said, “This is what the king who will reign over you will claim as his rights: He will take your sons and make them serve with his chariots and horses, and they will run in front of his chariots. 12 Some he will assign to be commanders of thousands and commanders of fifties, and others to plow his ground and reap his harvest, and still others to make weapons of war and equipment for his chariots. 13 He will take your daughters to be perfumers and cooks and bakers. 14 He will take the best of your fields and vineyards and olive groves and give them to his attendants. 15 He will take a tenth of your grain and of your vintage and give it to his officials and attendants. 16 Your male and female servants and the best of your cattle[c] and donkeys he will take for his own use. 17 He will take a tenth of your flocks, and you yourselves will become his slaves. 18 When that day comes, you will cry out for relief from the king you have chosen, but the Lord will not answer you in that day.” 19 But the people refused to listen to Samuel. “No!” they said. “We want a king over us. 20 Then we will be like all the other nations, with a king to lead us and to go out before us and fight our battles.” 21 When Samuel heard all that the people said, he repeated it before the Lord. 22 The Lord answered, “Listen to them and give them a king.” Then Samuel said to the Israelites, “Everyone go back to your own town.” (https://www.biblegateway.com/passage/?search=1+samuel+8&version=NIV)
At first Saul didn't want the kingship, he even hid! But after tasting victory and hearing the people's praises he became confident. Unfortunately, his confidence was not in the Lord, but in himself and in the praises of the people.
It's easy to be a "Sunday Christian" - have all the appearance of someone who goes to church, has it all together - dresses the part, brings the Bible and notebook, says the "christian" words. But life with Jesus is not about Sunday, it's about Everyday!
God doesn't want us going around saying we love Him. He wants us to love him AND be obedient. Saul had the appearance of following God - doing the kingly things that 'showed' he followed God, but his heart - what was beneath the water line of life where no one else could see - was not with God. His heart was with getting the praise and songs of the people.
In 1 Samuel 15, we read about the battle with the Amalekites, and how Saul disobeyed God's commands. The disobedience led to God regretting his decision to make Saul king!
"...Then the word of the Lord came to Samuel: “I regret that I have made Saul king, because he has turned away from me and has not carried out my instructions.” Samuel was angry, and he cried out to the Lord all that night..." 1 Samueld 15:11 (NIV, Bible Gateway)
Are we disobeying God to cause him regret? Do we break his heart by our words, thoughts and actions? Do we seek the praise of people over our relationship with God?
We stand in righteousness because of Jesus Christ. We do not stand in righteousness on our own merit. There was a judgement that secured our righteousness - it was a death sentence. Jesus paid the price on the cross for me and for you.
We often say, "its not my fault". That's what Saul did. He kept trying to shift responsibility. We today, often do the same thing. And then when found out, we are remorseful. But remorse is no substitute for repentance. Human applause is no substitute for divine approval.