Genesis 4:25 And Adam knew his wife again; and she bare a son, and called his name Seth: For God, said she, hath appointed me another seed instead of Abel, whom Cain slew.
26 And to Seth, to him also there was born a son; and he called his name Enos: then began men to call upon the name of the Lord.
Genesis 4:4-5, 4 And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the Lord had respect unto Abel and to his offering:
5 But unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.
6 And the Lord said unto Cain, Why art thou wroth? and why is thy countenance fallen?
7 If thou doest well, shalt thou not be accepted? and if thou doest not well, sin lieth at the door. And unto thee shall be his desire, and thou shalt rule over him.
When life pokes a hole in your plans faith steps up to fill in the plug with something better. In my sight, Seth is like a representative of the Holy Spirit in that through Seth men began to return to their first love, Jehovah GOD, The Father. The Holy Spirit directs man to call upon GOD, evokes worship. Seth is the manifestation of what GOD was staying in faith for to begin the lineage of the house of David.
We need to know that Abel, whom GOD loved, was righteous before GOD and became the hope to begin the process of salvation. Abel was a reverent specimen of obedient love. Abel was designed to be the beginning of the house of David. But Cain killed his own brother Abel. Jesus came out of the line of David. Mary and Joseph were chosen to carry the promise of GOD, His only begotten Son Jesus.
You may wonder why didn't GOD just form more dust and make another man. The answer is
because GOD decreed for Adam and Eve to fill the earth with their offspring from their loins forming another man from the dust of the ground is a violation of GOD's word.
Cain and Abel being the only two sons of Adam and Eve. Abel honored GOD with his offerings. Cain despised GOD and as a result gave GOD the worst of all he had. Cain offered GOD dog scraps. You can read that in Genesis 4:1-8.
Reference Genesis 2:7, 7 And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul. KJV, www.biblegateway.com
Numbers 23:19, 19 God is not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do it? or hath he spoken, and shall he not make it good? KJV, www.biblegateway.com
Now faith is the substance of things hoped for, the evidence of things not seen.
2 For by it the elders obtained a good report.
3 Through faith we understand that the worlds were framed by the word of God, so that things which are seen were not made of things which do appear.
4 By faith Abel offered unto God a more excellent sacrifice than Cain, by which he obtained witness that he was righteous, God testifying of his gifts: and by it he being dead yet speaketh.
5 By faith Enoch was translated that he should not see death; and was not found, because God had translated him: for before his translation he had this testimony, that he pleased God.
6 But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him. KJV, www.biblegateway.com