Learning SEO is not that difficult, but it depends on your intelligence, talent, accuracy and familiarity. You may be confused at the beginning of learning SEO or it may seem overwhelming to you, but in this case, you should continue to learn it.
Please note that SEO is like an experimental science and not all the techniques you learn in this field are applicable everywhere. More precisely, one SEO technique may help you succeed in a particular project, but the same technique in another project may cause you to fail and lose your credibility as an SEO professional.
So you have to learn how and where to use each technique to achieve the desired result.